Printers that print loose, single sheet documents are well known. In the case of many point-of-sale printers, a printer must be capable of printing on a sheet that is wider than the printer. For example, a 4″ wide printer must be able to print on one side of an 8½″×11″ sheet. Documents to be printed can include preprinted forms that are 8½″×11″ or A4, for example, as well as narrower documents such as receipts, checks, etc. Accordingly, to accommodate for documents that are wider than the printer, one side of the printer must be open, e.g., slotted, to allow wider sheets to be feed. For ease of discussion, the terms document and sheet are used interchangeably. A document can be a blank sheet or a pre-printed sheet. Alternatively, a document can be a multi-part or multi-ply form, with or without carbon paper. A sheet is typically of paper but is not limited to paper.
FIG. 1 is a perspective-view photo of a printer 50 with its cover closed and an 8.5″×11″ sheet 52 in the printer 50. The printer 50 includes a main portion 54 and a front portion 56 that is coupled to the main portion 54. The front portion 56 is separated from the main portion 54 and positioned relative to the main portion 54 such that a slot 58 is created through which the sheet 52 can be fed.
FIG. 2 is a top-view diagram of a conventional document feeder device 60, which can be used to implement the printer 50 of FIG. 1. Still referring to FIG. 2, the feeder device 60 advances the sheet 52 along a paper path in the slot 58. The document feeder device 60 includes a set of rollers 62-68 disposed around a pair of roller shafts 70 and 72. The sheet 52 is placed parallel to the shafts 70 and 72 and between the rollers 62-68. The roller shafts 70 and 72 rotate in opposite directions to advance the sheet 52 through the printer 50. Because the sheet 52 is wider than the printer 50, the document feeder device 60 is designed to feed the sheet 52 through the slot 58 of the printer 50. The slot 58 is created by a separation between a main portion 54 and a front portion 56 of the printer frame.
A problem with the conventional document feeder device 60 is that if any of the roller shafts 70 and 72 become misaligned, the sheet 52 will skew as it advances through the rollers 62-68. Accordingly, to ensure reliable performance, i.e., accurate paper feeds, the document feeder device 60 is designed to maintain adequate alignment with other components of the document-feed assembly 60 and be designed for maximum stability. Accordingly, to keep the roller shafts 70 and 72 as rigid as possible with maximize stability, the ends of the roller shafts 70 and 72 are directly connected and supported by portions of the printer frame. Specifically, the ends of the roller shaft 70 are directly connected to and supported by bearings 74 and 76, which are connected to and supported by frame supports 78 and 80, respectively. Also, the ends of the roller shaft 72 are directly connected to and supported by bearings 82 and 84, which are connected to and supported by frame supports 86 and 88, respectively. The frame supports 78 and 80 are part of the main portion 54 of the printer frame, and the frame supports 86 and 88 are part of the front portion 56 of the printer frame.
The problem with the conventional document feeder device 60 is that is difficult to provide an adequately rigid and stable mounting surface for the roller shaft 72 when there is a slot 58 separating the main and front portions 54 and 56 of the printer 50. This difficulty exists because if the front portion 56 moves, the frame supports 86 and 88 also move because they are integrated into the front portion 56. The front portion 56 can move due to various reasons. For example, a user might lean on the front portion 56 or might place a heavy object on it, pushing it downward.
Unfortunately, a slight movement of the front portion 56 causes a substantial misalignment between the roller shafts 70 and 72, because the degrees of movement of the frame supports 86 and 88 differ. This difference is created upon movement of the front portion 56 because it is connected to the main portion 54 on one side only, i.e., the left side. For example, if the front portion 56 droops or lowers in any way, the frame support 86 will lower further than the frame support 88. The longer the distance between the frame supports 86 and 88, the larger the magnification. Unfortunately, there is not a way to bridge a support across the front and main portions 54 and 56 without obstructing the paper path.
One conventional solution to the problem is to make the overall printer frame, including the connection between the front and main portions 54 and 56 as rigid as possible. However, doing so increases the cost of production by requiring additional frame hardware and/or more rigid frame hardware.
Accordingly, what is needed is an improved system and method for providing a document feeder device that can more reliably feed documents through a printer. The system and method should be cost effective and easily implemented in existing designs. The present invention addresses such a need.